package license

import (
	"encoding/base64"
	"encoding/json"
	"license-server/storage"
	"time"

	"github.com/gofiber/fiber/v2"
)

func GenerateLicenseHandler(db storage.Database) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var req LicenseRequest
		if err := c.BodyParser(&req); err != nil {
			return fiber.ErrBadRequest
		}

		payloadBytes, _ := json.Marshal(req)
		payloadB64 := base64.StdEncoding.EncodeToString(payloadBytes)
		signature, _ := SignPayload(payloadBytes)

		licenseFile := LicenseFile{
			Payload:   payloadB64,
			Signature: signature,
		}

		return c.JSON(licenseFile)
	}
}

func ActivateLicenseHandler(db storage.Database) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var lf LicenseFile
		if err := c.BodyParser(&lf); err != nil {
			return fiber.ErrBadRequest
		}

		payloadBytes, _ := base64.StdEncoding.DecodeString(lf.Payload)
		var req LicenseRequest
		json.Unmarshal(payloadBytes, &req)

		if db.HasActivated(req.MachineID) {
			return fiber.NewError(403, "This machine is already activated.")
		}

		if !VerifySignature(&privateKey.PublicKey, payloadBytes, lf.Signature) {
			return fiber.NewError(401, "Invalid license signature")
		}

		licenseText := lf.Payload + "." + lf.Signature
		db.SaveActivation(req.MachineID, licenseText)

		return c.SendString("License activated successfully.")
	}
}

func ValidateLicenseHandler(db storage.Database) fiber.Handler {
	return func(c *fiber.Ctx) error {
		var lf LicenseFile
		if err := c.BodyParser(&lf); err != nil {
			return fiber.ErrBadRequest
		}

		payloadBytes, err := base64.StdEncoding.DecodeString(lf.Payload)
		if err != nil {
			return fiber.NewError(fiber.StatusBadRequest, "Invalid payload encoding")
		}

		// 先验证签名是否真的是对 payloadBytes 签的
		if !VerifySignature(&privateKey.PublicKey, payloadBytes, lf.Signature) {
			return fiber.NewError(fiber.StatusUnauthorized, "Invalid license signature")
		}

		// 验证通过后再解析 payload 内容
		var req LicenseRequest
		if err := json.Unmarshal(payloadBytes, &req); err != nil {
			return fiber.NewError(fiber.StatusBadRequest, "Malformed payload")
		}

		expiry, err := time.Parse("2006-01-02", req.Expiry)
		if err != nil {
			return fiber.NewError(fiber.StatusBadRequest, "Invalid expiry date")
		}
		if time.Now().After(expiry) {
			return fiber.NewError(fiber.StatusForbidden, "License expired")
		}

		return c.JSON(fiber.Map{"valid": true, "features": req.Features})
	}
}